Indicators Of Heavy Metal Contamination Research Articles

Identification of a Biochemical Indicator in Plants for Heavy Metal Contamination

Aims: To identify a biochemical parameter in a plant(s) that can serve as an indicator of heavy metal pollution. Study Design: Design of the study includes collection of plant samples from a contaminated site and a rural site and to check their biochemical parameters related to oxidative stress. Based on the experimental findings, attempts were made to identify a parameter that can serve as an indicator of heavy metal contamination. Place and Duration of Study: The study was conducted in Department of Biotechnology, Heritage Institute of Technology, India, during the period from August 2013-June 2014. Methodology: Plant samples were collected from East Calcutta Wetlands (metal contaminated site) and Binogram, a village 90 Km away from Kolkata (control site). The samples were checked for the following parameters: non-protein thiol, ascorbic acid, superoxide dismutase (SOD), lipid peroxidation. This was followed by a statistical analysis. Results: Non-protein thiol content was found to be less in the Ipomoea, Hygrophila and cabbage Original Research Article Das et al.; BBJ, 5(3): 148-155, 2015; Article no.BBJ.2015.014 149 samples collected from ECW. The values were 65-75% of the village samples. Cauliflower leaves did not show any alteration in the parameter. Ascorbic acid was altered significantly in cabbage and Hygrophila. Activity of SOD decreased in all samples. Lipid peroxidation increased in all samples except Ipomoea. Of the biochemical parameters tested, maximum alteration was found with nonprotein thiol, in which glutathione (GSH) is the major constituent. Of the vegetables studied, cabbage showed an alteration in all biochemical parameters. Conclusion: GSH has the potential for being used as an indicator of heavy metal pollution. Cabbage can be used as a model vegetable for testing the biochemical parameters. The method will be helpful in identification of a contaminated site before estimation of heavy metals.

Magnetic susceptibility as an indicator of heavy metal contamination of urban soils (Review)

Researchers have a particular interest in the assessment of magnetic susceptibility due to aerial contamination of soils by magnetite and heavy metals. The content of magnetite and other magnetic minerals in urban soils is tens and hundreds of times higher than their background values. The properties of technogenic magnetics are also different: whereas background soils are dominated by thin superparamagnetic and single-domain particles, large multidomain particles prevail in urban soils. Technogenic magnetics consist of micron-sized spherules. It has been proven that there is a correlation between magnetic susceptibility and the total content of heavy metals in soil. However, each city (or its district) has its own level, either positive or negative, which is determined by the nature of local contamination. Magnetic susceptibility maps have been created even for some countries (Poland, United Kingdom, etc.). Local surveys of urban areas, for example of a city or its vicinity, is of the greatest practical interest. Such maps reflect detailed contamination by heavy metals. Critical values of magnetic susceptibility above which soil is considered contaminated, differ between countries.

Kinetics of bioaccumulation of heavy metals in Odontesthes bonariensis is explained by a single and common mechanism

Fish are often considered a very sensitive indicator of heavy metal contamination in aquatic ecosystems; however, the detailed mechanisms of bioaccumulation remain unclear. Here, we study the bioaccumulation processes of three relevant heavy metals (Cd2+, Cu2+ and Cr6+) in Odontesthes bonariensis using mathematical modelling. We developed a general compartmental kinetic model that describes the transport of heavy metals between the surrounding water and the gills and liver of fish. The general model was reduced to a simple one still capable of reproducing previous experimental data and suggesting a common mechanism for the three metals. The modelling results indicate that bioaccumulation of Cd2+, Cu2+, and Cr6+ is described by a combination of a concentration-independent and saturable uptake kinetics in both organs with a unidirectional path of elimination from gills to liver to waterborne. Finally, the good agreement between the parameter values predicted by the model and previously published data suggests that our modelling approach may shed light on the mechanisms of heavy metal bioaccumulation in other species.

Characterization of Heavy Metal and Antibiotic Resistant Bacteria Isolated from Aliaga Ship Dismantling Zone, Eastern Aegean Sea, Turkey

In this study, it was aimed to determine the effects of ship dismantling zones on distribution ofheavy metal resistance and level of antibiotic resistance of bacterial isolates from Eastern Aegean Sea coast.Thirteen isolates were identified by phylogenetic analysis using 16S rDNA sequences which indicated that theisolates belonged to genus Bacillus. These strains were investigated in respect of the minimum inhibitoryconcentrations (MICs) of heavy metals (Hg, Cu, Cd, Cr, Zn, Co, Ni, Pb and As) and susceptibility of someantibiotics (ampicillin, tetracycline, chloramphenicol, vancomycin, gentamicin and tobramycin). The MICs ofheavy metals were different for each strain but the general order of resistance to the metals was found to be as Pb>As>Ni>Co>Cu>Zn>Cr>Cd>Hg and the toxic effects of these metals increased with increasing concentration. It can be concluded that all isolates were sensitive to Hg but were highly resistant to Pb, As and Ni. Additionally, it was found that the strains were resistant to gentamicin followed by tobramicin. The studies suggest that sediment bacteria in a ship dismantling area can be biological indicators of heavy metal contamination.

Reduced glutathione and acetylcholinesterase expressions in Perna indica exposed to trivalent arsenic

In the present study Indian brown mussel, Perna indica was exposed to 20, 40, 80, 160 and 320 ppb (µg/l) arsenic concentrations under short-term chronic toxicity bioassay (14 days) for the assessment of reduced glutathione and acetylcholinesterase as potential biochemical biomarkers in arsenic pollution. A higher level of reduced glutathione (GSH) and increased acetylcholinesterase (AchE) activity was expressed when compared to control in 160 and 320 ppb arsenic concentration. The found values were significant at P<0.01. The values of total protein were significantly lower (P<0.05) in all the exposed concentration when compared with control. This study suggests that metabolites and antioxidant enzymes activity was affected by heavy metal exposures and strongly have the potential as indicators of heavy metal contamination and arsenic in specific. Hence, the determination of oxidative stress biomarkers in Perna indica may serve as a convenient approach during pollution biomonitoring programme.

Bioaccumulation of heavy metals in the wolf spider, Pardosa astrigera L. Koch (Araneae: Lycosidae)

Previous studies have proposed that Pardosa astrigera L. Koch (Lycosidae) can be used as a biological indicator of heavy metal contamination in soil. In this study, we estimated the bioaccumulation levels and the bioconcentration factors (BCF) of four heavy metals (Cd, Cu, Pb, and Zn) in adult female P. astrigera collected from various field sites according to heavy metal content gradient and broods. The relationship between heavy metal content in the soil and that in spiders was different depending on the heavy metals and the broods. However, heavy metal content in P. astrigera increased with increasing heavy metal content in the soil. While the heavy metal content in the soil was in the order of Zn > Pb > Cu > Cd, its content in P. astrigera was in the order Zn > Cu > Cd > Pb. The BCF for Cd in both of the broods was distinctly higher than those of the other heavy metals evaluated. These results indicate that P. astrigera may be useful as a biological indicator of Cd soil contamination.

Assessment and characterization of heavy metal resistance in Palk Bay sediment bacteria

The present study aimed at characterizing the heavy metal resistance and assessing the resistance pattern to multiple heavy metals (300 mmol L −1) by Palk Bay sediment bacteria. From 46 isolates, 24 isolates showed resistance to more than eight heavy metals. Among the 24 isolates S8-06 ( Bacillus arsenicus), S8-10 ( Bacillus pumilus), S8-14 ( B. arsenicus), S6-01 ( Bacillus indicus), S6-04 ( Bacillus clausii), SS-06 ( Planococcus maritimus) and SS-08 ( Staphylococcus pasteuri) exhibited high resistance against arsenic, mercury, cobalt, cadmium, lead and selenium. Plasmid curing confirmed that the heavy metal resistance in S8-10 is chromosomal borne. Upon treatment with the heavy metals, the strain S8-10 showed many morphological and physiological changes as shown by SEM, FTIR and AAS analysis. S8-10 removed 47% of cadmium and 96% of lead from the growth medium. The study suggests that sediment bacteria can be biological indicators of heavy metal contamination.

Liver, gills, and skin histopathology and heavy metal content of the Danube sterlet (Acipenser ruthenus Linnaeus, 1758)

The sterlet (Acipenser ruthenus L.) is a bottom-feeding fish species with a direct exposure to contaminants from water and sediments. Although heavy metal pollution is believed to be one of the main threats to the sterlet population in the Danube River basin, there is a lack of knowledge of the exact impact of heavy metals on their survival. In the present study, effects of heavy metal pollution on sterlet in the Danube basin were assessed as well as the utility of different sterlet organs and tissues as indicators of heavy metal contamination. The sterlet were sampled at three different sites in the Danube basin, in Hungary and Serbia, isolated from each other by dams. Heavy metal analysis included measurement of Cd, As, Pb, Cr, Hg, Cu, Ni, Fe, Mn, and Zn concentrations in sterlet gills, muscle, liver, and intestine, and histopathological analyses comprised assessment and scoring of the extent and intensity of alterations in skin, gills, and liver tissue. Analysis revealed a significant presence of sublethal histopathological changes that were most pronounced in the liver and skin and increased accumulation of heavy metals, with the highest concentrations in the liver. Canonical discriminant analysis showed significant differentiation among the three studied localities, suggesting that the heavy metal concentrations in sterlet populations were site specific. The present study concludes that the accumulation of heavy metals is a response to the presence of these pollutants in the environment, and, together with other pollutants, it affects the vital organs of natural sterlet populations.

Magnetic susceptibility as an indicator of heavy metal contamination in compost

One of the main restrictions to the agronomic use of compost is the excess of heavy metals, which are often present due to inadequate separation of biodegradable fractions from non-degradable or inert materials. Magnetic susceptibility (MS) measurements are a simple technique that has been reported as a useful tool for assessing anthropogenic pollution, especially heavy metal pollution on soil and sediment samples. The close relationship of MS with heavy metal contamination has been proved by combined analyses of chemical and magnetic data. In this study, the MS and total heavy metal concentrations of eight composts from different origins were determined; all composts were passed under a magnet to remove the magnetic material, and total heavy metals were determined again. In our work, high correlations were found between magnetic susceptibility and total Cd, Zn, Pb, Cr and Ni, thus confirming the applicability of MS measurement as a proxy for heavy metal contamination in compost quality assessments. The application of a magnet over the composts reduced the MS as well as the heavy metal content, the reduction of Fe and MS being the most significantly correlated. Thus, the inclusion of an additional magnetic separation step in the post-process compost finishing could be envisaged.

Nematodes as indicators of soil recovery in tailings of a lead/zinc mine

Trophic groups and functional guilds of soil nematodes were measured under four mine tailing subsystems in the Baoshan lead/zinc mine, Hunan Province, southern China to test the indicator value of nematodes for heavy metal pollution. No obvious correlation was found between heavy metal concentration and the total number of nematodes. However, the densities of c–p3, c–p4 and c–p5 nematodes were negatively correlated with Pb and Zn concentrations, suggesting that the abundance of nematode groups of high c–p values is useful indicators of heavy metal contamination. The “weighted faunal analysis” provided a better assessment of soil health condition than Maturity Index (MI) in situations where there were extremely low numbers of soil nematodes. Results showed that the effect of heavy metal contamination on soil nematodes might be strongly influenced by plants. Although the abundance of plant-feeding nematodes did not reflect the heavy metal conditions in the soil, it might be used as an index for assessing the soil remediation potential of pioneering plants. Patrinia villosa seems superior to Viola baoshanensis as a pioneer plant species for soil remediation based on analysis of rhizosphere nematode community.

Antioxidant Enzymes and Heavy Metal Levels in Tissues of the Black Chocolate Clam Megapitaria squalida in Bahía de La Paz, Mexico

The black chocolate clam Megapitaria squalida is a commercially important bivalve along the Pacific coast of Mexico and is used as a bioindicator in environmental health studies. Previous studies of Bahía de La Paz indicated significant differences in heavy metal content among localities in this clam. To identify areas affected by heavy metal pollution, lipid peroxidation (TBARS) levels and activity of superoxide dismutase (SOD) and glutathione S-transferase (GST) were measured in muscle, gonad, and digestive gland tissue and correlated with heavy metal levels of clams from six localities along the shore of the bay. Significant differences in TBARS levels and antioxidant enzyme activity were found among these tissues at all localities. Such differences are ascribed to the physiology of each organ. Higher levels of TBARS were found in areas with higher cadmium content. SOD activity in muscle correlated positively with cadmium, lead, and iron in areas with a higher content of those elements. This study suggests that TBARS levels and SOD and GST activity are affected by biotic and abiotic factors and have potential as indicators of heavy metal contamination.

Microbial indicators of heavy metal contamination in urban and rural soils

Urban soils and especially their microbiology have been a neglected area of study. In this paper, we report on microbial properties of urban soils compared to rural soils of similar lithogenic origin in the vicinity of Aberdeen city. Significant differences in basal respiration rates, microbial biomass and ecophysiological parameters were found in urban soils compared to rural soils. Analysis of community level physiological profiles (CLPP) of micro-organisms showed they consumed C sources faster in urban soils to maintain the same level activity as those in rural soils. Cu, Pb, Zn and Ni were the principal elements that had accumulated in urban soils compared with their rural counterparts with Pb being the most significant metal to distinguish urban soils from rural soils. Sequential extraction showed the final residue after extraction was normally the highest proportion except for Pb, for which the hydroxylamine-hydrochloride extractable Pb was the largest part. Acetic acid extractable fraction of Cd, Cu, Ni, Pb and Zn were higher in urban soils and aqua regia extractable fraction were lower suggesting an elevated availability of heavy metals in urban soils. Correlation analyses between different microbial indicators (basal respiration, biomass-C, and sole C source tests) and heavy metal fractions indicated that basal respiration was negatively correlated with soil Cd, Cu, Ni and Zn inputs while soil microbial biomass was only significantly correlated with Pb. However, both exchangeable and iron- and manganese-bound Ni fractions were mostly responsible for shift of the soil microbial community level physiological profiles (sole C source tests). These data suggest soil microbial indicators can be useful indicators of pollutant heavy metal stress on the health of urban soils.

Use of Skin and Blood as Nonlethal Indicators of Heavy Metal Contamination in Northern Water Snakes (Nerodia sipedon)

Relatively little is known about contaminants in reptiles, particularly snakes. The concentrations of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium were examined in blood and skin of 46 northern water snakes (Nerodia sipedon) in Tennessee and correlated with concentrations in internal tissues (liver, kidney, muscle) to determine if blood or skin could serve as a nonlethal indicator of internal metal exposure or body burden. Snakes were collected from the East Fork Poplar Creek (EFPC) within the United States Department of Energy's Y-12 National Security Complex (part of the Oak Ridge National Laboratory) and from a reference stretch of the Little River in East Tennessee. For blood, the only consistent positive correlations with internal organs were for mercury, and correlations were low except for muscle. Skin showed significant positive correlations with all three organs for mercury, chromium, selenium, and lead. For manganese and cadmium, skin level was positively correlated with liver level. Blood generally reflects recent exposure, not necessarily body burden, but in water snakes it correlates with body burden for mercury. Skin proved useful for more metals, although patterns were not necessarily consistent across sex and locality subgroups. The most consistent pattern was for mercury, the metal of greatest concern in many aquatic ecosystems, including EFPC.

The feasibility of using introduced lizards as indicators of environmental contamination

Introduced species can provide valuable opportunities for applied research once they have become established with little possibility of eradication. They have been used as indicators of environmental contamination in aquatic ecosystems for many years. However, in terrestrial ecosystems, introduced species have not been utilized as sentinels of environmental quality. We review the feasibility of using species of lizards that have been introduced, are closely related to species that have been introduced, or have the potential of being introduced to the United States, as indicators of heavy metal contamination. Metal concentrations in lizards were compared from the few available studies, including one recently conducted on the introduced brown anole Anolis sagrei in southern Florida. Brown anoles, tropical house geckos Hemidactylus mabouia, sand lizardsLacerta agilis, common viviparous lizards Lacerta vivipara, common wall lizards Podarcis muralis, and starred agamas Laudakia (Agama) stellio stellio were shown to be suitable indicators of heavy metal pollution because differences were found in metal levels in lizards from different locations within a given region, and lizards from sites presumed to be contaminated by heavy metals contained higher metal concentrations than those from locations that were uncontaminated.

Determining rates of change and evaluating group-level resiliency differences in hyporheic microbial communities in response to fluvial heavy-metal deposition.

Prior field studies by our group have demonstrated a relationship between fluvial deposition of heavy metals and hyporheic-zone microbial community structure. Here, we determined the rates of change in hyporheic microbial communities in response to heavy-metal contamination and assessed group-level differences in resiliency in response to heavy metals. A controlled laboratory study was performed using 20 flowthrough river mesocosms and a repeated-measurement factorial design. A single hyporheic microbial community was exposed to five different levels of an environmentally relevant metal treatment (0, 4, 8, 16, and 30% sterilized contaminated sediments). Community-level responses were monitored at 1, 2, 4, 8, and 12 weeks via denaturing gradient gel electrophoresis and quantitative PCR using group-specific primer sets for indigenous populations most closely related to the alpha-, beta-, and gamma-proteobacteria. There was a consistent, strong curvilinear relationship between community composition and heavy-metal contamination (R(2) = 0.83; P < 0.001), which was evident after only 7 days of metal exposure (i.e., short-term response). The abundance of each phylogenetic group was negatively affected by the heavy-metal treatments; however, each group recovered from the metal treatments to a different extent and at a unique rate during the course of the experiment. The structure of hyporheic microbial communities responded rapidly and at contamination levels an order of magnitude lower than those shown to elicit a response in aquatic macroinvertebrate assemblages. These studies indicate that hyporheic microbial communities are a sensitive and useful indicator of heavy-metal contamination in streams.

DNA damage induced by copper on erythrocytes of gilthead sea bream Sparus aurata and mollusk Scapharca inaequivalvis.

Heavy metal pollution in rivers and its impact on aquatic ecosystems is a dynamic process. Fish are ideal indicators of heavy metal contamination in aquatic systems because they occupy different trophic levels and are of different sizes and ages. In particular, copper is an essential trace metal for living organisms and it is present in all natural waters and sediments. In this paper, we report data on the effect of copper on DNA erythrocytes from the teleost gilthead sea bream Sparus aurata and the bivalve mollusk Scapharca inaequivalvis. In particular, the effect of 0.1 ppm of Cu2+ on the nucleated erythrocytes was analyzed using the "comet assay." This test is a promising tool for estimation of DNA damage at the single cell level. The data obtained show that the in vivo treatment with 0.1 ppm of copper increased the susceptibility of DNA to be damaged. Exposure to Cu2+ produces a more evident effect on Sparus aurata, as all three comet parameters significantly increased (tail length, tail intensity, and tail moment). The higher comet parameters measured in Scapharca inaequivalvis compared to Sparus aurata could be due to the difference in stability of the respective hemoglobins. The comet assay could represent a useful test to evaluate the biological consequences of environmental contamination by metals on marine organisms.

Diversity and structure of Chironomidae (Diptera) communities along a gradient of heavy metal contamination in a subarctic watercourse

Community structure of chironomid larvae was investigated along a gradient of heavy metal pollution in the subarctic lakes of the Pasvik watercourse, bordering Northern Norway and Russia. Sixty taxa were present in the four investigated lakes. Species richness was lower in Lake Kuetsjarvi, nearest the main source of pollution, relative to the more distant lakes, and Simpson's diversity index was similarly highest in the less polluted site with higher maximum depth. The number of orthoclad chironomid species was considerably higher at the least contaminated sites, whereas the relative abundance of Orthocladiinae was highest at the most polluted site. Chironomid density increased with increasing distance from the main source of heavy metal pollution, especially in the subfamilies Tanypodinae and Chironominae, and total chironomid biomass was significantly higher at the least polluted site. Canonical correspondence analysis revealed spatial patterns consistent with species-specific tolerance to the heavy metal concentrations. Protanypus morio, Monodiamesa bathyphila, Chironomus spp., Polypedilum scalaenum gr. and Sergentia coracina seemed to be tolerant to heavy metal contamination, occurring most commonly at the most polluted sites. In contrast, Heterotrissocladius subpilosus, Psectrocladius semicirculatus/sp. , Chironomus anthracinus, Pagastiella orophila, Cladotanytarsus iucundus, and Tanytarsus spp. appeared to be more sensitive taxa, being common at the least polluted sites, but rare or absent at the two sites close to the pollution sources. Densities of Procladius ( Holotanypus) spp., Tanytarsus spp. and Chironomus anthracinus were negatively correlated with heavy metal concentrations and these taxa appeared to be the best indicators of heavy metal contamination.

Metal Levels in Fish from the Savannah River: Potential Hazards to Fish and Other Receptors

Fish are ideal indicators of heavy metal contamination in aquatic systems because they occupy different trophic levels and are different sizes and ages. In this paper, we report concentrations of arsenic, cadmium, chromium, copper, lead, manganese, strontium88 and mercury in the muscle of 11 species of fish from the Savannah River near the Savannah River Site. We test the hypotheses that there are no locational, species, or trophic-level differences in contaminant levels. There were significant species differences for all metals; higher-trophic-level fish generally had higher levels of arsenic, chromium, and copper. There were relatively few locational differences, and where there were such differences, they were small. The relationships between body weight and contaminant levels were generally positive, except for strontium, where there was a negative correlation for bowfin (Amia cal va), bass (Micropterus salmoides), yellow perch (Perca flavescens), and shellcracker (Lepomis microlophus) and no relationship for the other species. The levels of most metals were similar to, or lower than, those for the United States generally, and the levels of metals in fish from the Savannah River do not appear to pose a health threat to the fish themselves or to higher-order consumers, based on levels known to cause effects.

The potential association between menta deformities and trace elements in Chironomidae (Diptera) taken from a heavy metal contaminated river.

Elevated morphological deformity rates in Chironomidae larvae have been attributed to such pollutants as oil tars, pesticides, organochlorines, and heavy metals. The potential of chironomids as biological indicators of heavy metal contamination and bioavailability in a contaminated ecosystem was assessed. Chironomid larvae and river sediment were collected from the Coeur d' Alene River system, Idaho, USA, contaminated with heavy metals from mining activities. Chironomid larvae collected at contaminated sites exhibited mouthpart deformity proportions between 3.8 and 10.3% compared to the control site of 0.9%. As, Cd, Cu, Ni, Pb, and Zn were determined in both larvae and sediment samples. Significant correlation between metal concentrations and deformity rates were observed for all metals except Ni. The data also suggests that feeding habits may influence differences in pollution tolerance among genera.

Enteromorpha flexuosa (Wulfen) J. Agardh (Chlorophyta: Ulvales)--evaluation as an indicator of heavy metal contamination in a tropical estuary.

The use of bioindicators for contaminant monitoring is popular in all sectors of the environment but quite often bioindicators are utilised without rigorous evaluation of their viability as an indicator. We report field and laboratory investigations into the value of a commonly found macroalga, Enteromorpha flexuosa (Wulfen) J. Agardh (Chlorophyta: Ulvales) as an indicator of copper, zinc and lead contamination in a tropical estuary in Fiji. In the laboratory, metal content of E. flexuosa after 60 days of growth in seawater containing increasing concentrations of the metals showed almost perfect correlation with metal concentrations in water for all three metals, and concentration factors obtained were generally higher than values reported for other species of Enteromorpha. Performance in the field was evaluated by a one-year monitoring of metals in E. flexuosa, water and sediments from a contaminated estuary. Metal concentrations in water were always below detection limits and field concentration factors could not be determined but the concentration of lead in E. flexuosa showed a high correlation with the lead content of sediments. Lack of such correlation for copper and zinc in the field suggests that other environmental factors besides metal load in the physical environment could be controlling the bioaccumulation of these two metals. Whilst demonstrating E. flexuosa to be a viable bioindicator for lead, these results also highlight the need for proper assessment before an organism is considered for environmental monitoring.